86 lines
2.3 KiB
C++
86 lines
2.3 KiB
C++
/*
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epple2
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Copyright (C) 2008 by Christopher A. Mosher <cmosher01@gmail.com>
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY, without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "videoaddressing.h"
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#include "e2const.h"
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VideoAddressing::VideoAddressing()
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{
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}
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static int calc(const unsigned int t)
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{
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int c = t % E2Const::VISIBLE_BYTES_PER_FIELD;
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if (t >= E2Const::SCANNABLE_BYTES)
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{
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c -= E2Const::RESET_BYTES;
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}
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int n = c / E2Const::BYTES_PER_ROW;
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const int s = (n >> 6);
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n -= s << 6;
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const int q = (n >> 3);
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n -= q << 3;
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const int base = (n<<10) + (q<<7) + E2Const::VISIBLE_BYTES_PER_ROW*s;
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const int half_page = base & 0xFF80;
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int a = base+(c%E2Const::BYTES_PER_ROW)-E2Const::BLANKED_BYTES_PER_ROW;
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if (a < half_page)
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{
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a += 0x80;
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}
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return a;
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}
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void VideoAddressing::buildLUT(const unsigned short base, const unsigned short len, std::vector<unsigned short>& lut)
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{
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lut.resize(E2Const::BYTES_PER_FIELD);
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for (unsigned int t = 0; t < E2Const::BYTES_PER_FIELD; ++t)
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{
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unsigned int off = (calc(t) % len);
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const unsigned int col = t % E2Const::BYTES_PER_ROW;
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const unsigned int row = t / E2Const::BYTES_PER_ROW;
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if (col < E2Const::BLANKED_BYTES_PER_ROW)
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{
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// HBL
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if (base < 0x1000)
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{
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off += 0x1000;
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}
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if (col == 0)
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{
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++off;
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}
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}
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if (row >= E2Const::VISIBLE_ROWS_PER_FIELD)
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{
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// VBL
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const int base2 = off & 0xFF80;
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off &= 0x7F;
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off -= 8;
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off &= 0x7F;
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off += base2;
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}
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lut[t] = base + off;
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}
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}
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